The US has accused Iran of seeking a "near-total information blockade" to silence anti-government protesters.

美国宣称，伊朗试图谋求“近乎全部的信息封锁”以使反政府者保持缄默。

The allegations came after opposition¹ supporters clashed with security forces as Iran marked the anniversary of the 1979 revolution.

The US government said it had information that the telephone network was taken down, SMS messages blocked, and internet communication "throttled²（节流，压制） ".

China and Burma have also been accused of blocking internet communication.

Analysts³ say some governments make strenuous⁴（费力的，艰苦的） efforts to block modern communications among opponents, with varying degrees of success.

The Iranian opposition had called its supporters on to the streets to mark the anniversary of the Iranian Revolution, with clashes reported in Tehran as well as other cities.

But reports suggest opposition rallies were dwarfed⁵（使矮小） by the huge turnout to hear President Mahmoud Ahmedinajad address the official celebrations.

State department spokesman PJ Crowley told reporters: "Iran has attempted a near total information blockade.

"And it is an unprecedented⁶ and overwhelming（压倒性的，势不可挡的） step, using force to intimidate⁷（恐吓，胁迫） their own people and to restrict the freedom of assembly and the freedom of expression.

"It is clear that the Iranian government fears its own people."

He said his statement was based on US monitoring of communications within Iran.

Google said on Wednesday that Iranian users were having trouble accessing（访问） its Gmail service.

Reuters news agency quoted a Microsoft source as saying the company had not experienced any disruptions（分裂，破坏） to its Hotmail service in Iran.